Positraction Units, don't get stuck again!

We offer a wide selection of positractions to meet your specific application, why you need a positraction unit, when your vehicle is negotiating a corner, the outside wheel has to travel a grater distance than the inside wheel. Therefore, the outside wheel must turn faster than the inside wheel. The differential is the device within the axle assembly which, in addition to transmitting the power to each axle shaft/wheel, allows one wheel to turn at a different speed than the other.

There are many designs of Differentials including:

Conventional or Open

Limited Slip

Automatic Locking

Manual Locking

Conventional differential uses two side gears inside the differential case. Each gear is splinted to accept an axle shaft. These side gears are in turn driven by a set of spider gears. The spider gears, also inside the differential case, ride on a shaft which is pinned into the differential case and through which all the power is transmitted. The case is driven by the ring gear that is bolted fast to the case. The conventional differential is fitted as standard equipment on most vehicles.

On paved roads this system is very successful, giving predictable handling, even tire wear and requiring very little maintenance. However, in off road situations where traction surfaces vary greatly, this type of differential has a major limitation. When one wheel has greater traction than the other, all the power will be directed to the wheel with the least traction.

Limited slip differentials (LSD's) come in a variety of designs. Most use friction plates, cones and/or gears to reduce slippage between each of the tires. these units have a dual power path from the differential case to the axle shafts. Some power is transmitted through the spider gears to the side gears in the conventional manner. The remainder is transmitted by friction between the differential case and the clutch plates and the side gears.

Automatic locking differentials transmit power to each wheel through a pair of dog clutches. Differential action, such as when cornering is provided by automatically disengaging the appropriate clutch when one wheel rotates faster than the other. This results in differential action, that occurs in ratcheting stages rather than being smooth and progressive. Power received by the differential is automatically directed to the wheel with greater traction.

Manually lockable differentials use a conventional differential in conjunction with a mechanical locking device that can be operated at the driver's discretion. when locked, both axles will then turn at the same speed irrespective of the road surface. When it is unlocked, the differential functions as a conventional differential giving predictable handling, long service life and no increase in tire wear.

The Electric or Air Locker unit incorporates its activating mechanism totally inside the differential center. This avoids the need to have complicated piston arrangements hanging off the axle housing. Locking action is controlled by the drive with a push button switch inside the cab.

Select any of the following links to see detailed information on the featured positractions that we supply and design and application guide for your vehicle: